摘要
Spatial distribution characteristics of soil metals in Zhangye-Yongchang area of Gansu Province were studied in this paper.The results show that the study area is mainly characterized by the pollution of Cd,As,Cr and Ni.Industrial waste water and industrial enterprises,human activities and atmospheric dust constitute the major sources of soil pollution in the study area.Viewed from the comprehensive evaluation map of the degree of soil pollution,Grade one,Grade two,Grade three and Grade four quality areas possess 1.87%,87.13%,9.92% and 1.09% of the total area respectively.The current situation of soil pollution shows that heavy metals pollution in soil is mainly of Grade one and Grade two,which suggests the fairly good overall quality of the soil in the study area.Phase state analytical results of Cd,As,Cr and Ni show that Cd,As,Cr and Ni are mainly characterized by residual fraction.However,the Cd element is characterized by bound and soluble fractions,which account for about 5% of the total amount,and this situation is dangerous and deserves much attention.